Get the selected median point in python?
You can calculate it quite easy:

import bpy
from mathutils import Vector

ob = bpy.context.object
ob.update_from_editmode()

me = ob.data
verts_sel = [v.co for v in me.vertices if v.select]

pivot = sum(verts_sel, Vector()) / len(verts_sel)

print("Local:", pivot)
print("Global:", ob.matrix_world * pivot)


You could also use the bmesh module, but the standard API appears to be faster despite the update operation:

import bpy
import bmesh
from mathutils import Vector

ob = bpy.context.object
me = ob.data    

bm = bmesh.from_edit_mesh(me)
verts_sel = [v.co for v in bm.verts if v.select]

pivot = sum(verts_sel, Vector()) / len(verts_sel)

print("Local:", pivot)
print("Global:", ob.matrix_world * pivot)